1. Field of the Invention
This invention relates to homogeneous and stable dispersions of organosiloxane polymers in mineral oil and the process for the preparation.
2. Description of the Prior Art
The dispersions of polymeric organosiloxanes and mineral oil are employed in a wide variety of uses ranging from anti-static finishes on natural and synthetic fibers to antifoam agents in motor oils hydraulic fluids lubricants and greases. For many of these uses the mineral oil would be the major component. One vexing problem associated with dispersions is due to the inherent relative immiscibility of the organosiloxane polymers and mineral oils which form separate phases after a short period of time. To overcome this problem of phase separation various additives generally in the nature of emulsifiers have been employed, which are effective for the intended purposes but, characteristically increase the foaming tendencies of the mineral oil component. Another approach is described in U.S. Pat. No. 3,445,385 which discloses the use of organic ammonium complexes of clays of the montmorillonite group as dispersing agents. However, the stability of these "organophilic organo-anmonium bentonite" dispersions still falls short of that desired especially the storage stability required for long periods.
While the foregoing problem of compatibility is related to the dispersion per se, the use of organosiloxanes as anti-foam agents in mineral oil compositions presents another problem. In the preparation of oil compositions for use as motor oils, hydraulic fluids, lubricants, greases and the like, various additives are used to prevent sludging, deposition of gum and resinous materials or similar objectionable results. These additives are generally detergents which increase the foaming tendencies of the oil composition along with conventional antioxidants, pour point depressants, extreme pressure agents and the like. Organosiloxane polymers have been employed to combat such foaming of oil compositions. Unfortunately, however, the polysiloxanes which initially suppress foaming, lose their effectiveness in a relatively short period of time. Many materials have been suggested for prolonging the foam-inhibiting action of the polysiloxanes with generally indifferent success.
Any means for increasing the stability of the dispersion per se and extending the effectiveness of the foam suppressing characteristics of organosiloxane polymers in mineral oils would be advantageous.